Volume 73 Number 4 Article 5 Pages: 240-253
Year 2019 Month 10
Title: Noninfectious Bud-failure As a Model For Studying Age Related Genetic Disorders in Long-Lived Perennial Plants
Authors: Thomas Gradziel, and Jonathan Fresnedo
Plants disseminated through vegetative propagation avoid the meiotic recombination and associated
rejuvenation found during sexual seed propagation.
The resulting natural and human selected clones allow
accumulation of genetic as well as non-genetic (epigenetic) interactions as long as the studied trait remain trueto-
type following vegetative propagation.
The consequent ‘immortalization’ of the clone also allows large clonal
population sizes and long-term plant lifespans required for the later accumulation of budsport mutations in such
While both natural and human selection result in clones with desirable changes, the longterm
preservation of these clones also facilitate the occurance of genetic disorders.
In almond (Prunus dulcis, DA
Webb) Noninfectious Bud-failure (NBF) is an economically important disorder of California cultivars because
it severely affects two major commercial cultivars, ‘Nonpareil’ and ‘Carmel’, and has led to the abandonment of
many otherwise productive cultivars and breeding selections over the last half century.
NBF expression shows
some epigenetic characteristics including an increase in expression with tree as well as clone age, so that new
cultivars may possess the NBF factor but it remains latent for years to decades.
The resulting tree and clone
aging ‘time-bomb’ makes this disorder particularly devastating since extensive commercial plantings may have
been established before the disorder is first identified.
Because of this economic significance, clone lineage or
clone-source selection strategies have been developed to identify this disorder within breeding lineages as well
as within individual nursery propagation sources.
Proven though somewhat tedious phenotype-based methods
for identifying NBF-associated factors, both among and within genotypes have proven effective in 30 years of
Results from preliminary characterizations of DNA-(de)methylation profiling using methylationsensitive
amplified fragment length polymorphisms (MS-AFLP) targeting NBF and the related aging-process
within individual plants as well as within individual clones has provided promising insights.
in identifying both the mechanism as well as governing tissue for clonal age-memory in plants.
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